Thermal cut-out.



No. 799,598. PATBNTED SEPT. e, 1994.

' W. L. R. EMMET.

THERMAL GUT-OUT. APPLICATION FILED DEOA, 1899. N0 MODEL.

M l l im. @u i.

Patented September 6, 1904.

UNITED STATES PATENT OEEICE.

WILLIAM L. R. EMMET,"OF SCHENECTADY, NEIY YORK, ASSIGNOR TO THE GENERALELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

THERMAL CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 769,598, datedSeptember 6, 1904.

T0 all whom it may conoci-n.'

Be it known that I, VILLIAM LE ROY EMMET, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in Thermal Cut-Outs, of which the following is a specification.

This invention relates to thermal interrupters or cut-outs for electriccircuits, the object being to provide a device of this type which willsafely interrupt circuits of high potential and large amperage.

My invention,although generally applicable to current-interrupters, isespecially designed for use in shunt to circuit-breakers with currentsoi' high potential and large amperage, in which the maincircuit-terminals are iirst opened at the circuit-breakercontacts, thethermal device carrying the current for a sui'- iiciently long period topermit a sparkless opening of the circuit at the main terminals and thengiving way and extinguishing the arc, thus preventing damage to thecircuitbreaker contacts or other supporting parts. It is desirable to sodesign devices oi' this character that the fuses can be easily replaced.

I carry out my invention by mounting the fuse in a long plug containinga narrow opening with one or more enlargements of pockets at intervalsin the length oi' the fuse, the plug being covered with a removableenvelop, such as paper, and the whole adapted to be slipped into asupport in which openings correspondingly located to the pocket orpockets are provided to permit the expulsion of the gaseous products dueto the giving way of the fuse, over which opening or openings are placedchimneys to coniine or give direction to the escaping vapors. The fusemay be a fine copper wire or strip which gives way almost instantlythroughout its length and is vaporized, the gas escaping through thechimneys, its expulsive force extinguishing the arc. Thus the onlyelement damaged by the giving Way of the fuse is the paper envelop,which can be readily renewed, permitting the cutout to be used over andover again without deterioration. I provide a tube of insulatingmaterial-for example, woodbored at appropriate distances for the ventsabove referred to and suitably supported so that the plug containing thefuse maybe readily inserted and withdrawn. At the end oi' theinsulatingtube are provided circuit-terminals with sockets and contactsfor the fuse-terminals on the plug. Thus the examination oi' the fuse orthe replacement of one which has been blown by anew one is a very easymatter.

The novel features of my invention will be more fully describedhereinafter and will be deiinitely indicated in the claims.

In the accompanying drawings, which illustrate my invention, Figure l isa central sectional elevation through the insulation support of acut-out embodying my improvements. Fig. 2 is a vertical transversesection on the plane indicated by the line .fc .fc of Eig.

l. Fig. 3 is an end view looking from the left of Fig. l, showing thearrangement of the circuit-terminal for the socket into which the plugis inserted. Fig. 4: is a transverse section on a plane indicated by theline y y orl Fig. l. Fig. 5 is a sectional view oi' the plug at anintermediate point between the fuse-terminals.

I represents a base or support provided with bolt-holes, as indicated indotted lines.l to enable it to be clamped to the switchboard or othersuitable point where the device is to be used. It carries on its rearside two brackets 8O 2 2, wide spaced at the point of connection withthe support and coming' together to hold a carrier T'or theinsulating-tube at their lower ends. This carrier is formed ot' a plateof insulating material 3 and mounted on an in- 85 sulating-tube boltedto the brackets by means oi' the caps and washers oitl insulatingmaterial and bolt, as indicated clearly in Fig. 2.

A block of wood or other insulating material i, centrally bored, issupported in sheet-metal Yaands 5 bolted to the plate 3, and in order tostrengthen the tube it may be wire wound,

as indicated at 6 61. In the ends oil the tube are lagged metal collars7 7u, acting as guides and contacts for the fuse, secured to the plug byset-screws, as shown. Each collar carries a circuit-terminal 8 8, boredto form a loose iit and split on the inside to perand pushed over theplug.

mit clamping over the tube by a set-screw 9. (See Fig. 3.) Thecircuit-wires are set in a hole bored in the side of the terminal whereit is locked by set-screws 10. The fuse-plug' may be made of wood andprovided with a narrow longitudinal groove, such as 11, Fig. 2. In theends of this groove are inserted sheet-metal strips 12 12, riveted to ametal sleeve 13 13s, fastened to the plug at suitable distances toengage the sockets 7 7n. To these plates the fuse 14 may be fastened bysetscrews or any other convenient engaging device. Thus when the fuse isin place in the plug it lies snugly in the groove 11. At intervals inthe length of the slot are enlargements or pockets 15 15, Sac., oppositewhich vents 16 16a 16b are formed in the insulating'- support. Thesepockets are somewhat wider and deeper than the fuse-groove, therebypermitting the part of the fuse which extends through the pocket to beentirely surrounded by a gas or air medium and permittingarapid rise ofheat at this point when the fuse is overloaded relatively to the otherparts of the fuse, which are in contact with the walls of the groove andwhich therefore heat much more slowly, the result being that the fusegives way first at the pocket and fusion quickly eX- tends toward theterminals in both directions. Around these vents are mounted chimneys 1717a, liXed in countersunk annular holes bored in the support. The endterminal of the support carries a spring 18, the end of which is adaptedto snap into aslotcut transversely in the socket 7, thus acting to forcethe metal collar 13, connected with the fuse-terminal, into good contactwith the socket. Connection at the inner end may be effected by means ofa wire spring 19, mounted on the plug and projecting through a slot inthe terminal collar, the spring being provided with a curved engagingface, so as to permit insertion and withdrawal of the plug. In order toinsure proper alinement of the plug in inserting it in the support andpermit the springs to fall into their seats, I employ a guide, which maybe of any desired character; but the type shown is cheap and effective,comprising a slot in the plug-handle 20,which may be pushed home in itsseat when in alinement with a projecting pin 21, fastened to thesupport 1. Thus in connecting the cut-out into circuit the only actnecessary is to insert the plug in its socket and push it home.

ln order to prevent a distribution of the hot gaseous products of thearc along the plug', I provide a removable covering for the pockets 1515, Sac., for which I preferably employ paper, (see Fig. 5,) which maybe wound around or be employed in the form of a tube The paper tubemaybe provided with holes opposite the pockets and chimneys, asindicated. The tube acts as a gas-check, preventing the hot vapors beingdistributed over the inner wall of tube 4.

When the fuse blows, it melts first at the pockets and instantly spreadsalong the groove, the gases are driven forcibly out through the supportand chimneys, and the arc extinguished.

That I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. A fuse comprising a wire, a grooved support in which the wire restsand against which it bears throughout the major part of its length, andone or more enlargements of the groove leaving a free air-space allaround the Wire at a point or points desired to first give way, the saidwire being in contact with the grooved walls at all other points.

2. A cut-out comprising a socket provided with circuit-terminals atfront and rear and one or morevents in the socket-walls between saidterminals, and a plug connection adapted to be inserted and withdrawnquickly from the socket.

3. A thermal cut-out for electric circuits, comprising a socketcontaining elastic circuitterminals at front and rear and provided withone or more long vents intermediate its ends, and a removableplugcarrying a fuse adapted when the plug is inserted to automaticallyengage the terminals and extending across the vent or vents.

4. A thermal cut-out comprising a socket, a plug carrying a fuse adaptedto be quickly introduced into and withdrawn from said socket, elasticcircuit-terminals at the front and rear of the socket completed when theplug is inserted, one or more vents in the Walls of the socket, andcorresponding gas-pockets in the plug.

5. A cut-out comprising a socket provided with circuit-terminals, one ormore vents in its walls, a plug carrying a fuse adapted to connectelectrically with the terminals when inserted in the socket, said fuseextending transversely of the vent or vents, and a thin removable liningfor the socket.

6. A cut-out comprising a socket provided with circuit-terminals, one ormore vents in its walls, a plug carrying a fuse adapted to connectelectrically with the terminals when inserted in the socket, said fuseextendingtransversely of the Vent or vents, and a removable tubularseptum between the plug and socket.

7. A thermal cut-out comprising a socket, a plug carrying a fuse adaptedto be inserted into and withdrawn therefrom, circuit-terminals mountedon the socket adapted to be engaged by the fuse-terminals when the plugis inserted, one or more gas-pockets in the plug along IOO the fuse, apaper tube carried by the plug,

9. A thermal cut-out comprising an insulated tubular support, a plugadapted to be inserted into and Withdrawn therefrom, circuitterminalsconnected when the plug is inserted, a fuse mounted on the plug, one ormore vents for the gaseous products, when the fuse blows, and chimneysfor said vents.

10. A thermal cut-out comprising a tubular support, a plug carrying afuse adapted to be inserted into and Withdrawn therefrom, circuitconnections completed When the plug is inserted, a fuse mounted on theplug, Vents in the support opposite the fuse, and a guide for insuringalinement of the fuse with relation to the Vents when the plug isinserted.

ll. A thermal cut-out comprising a socket of insulating materialprovided With Vents in its Walls, a fuse-carrying plug adapted to beinserted in the socket, tubular terminals on the socket and plug, andsprings to hold them in hrm engagement When the plug is inserted.Y ,o

WILLIAM L. R. EMMET.

Vitnesses:

BENJAMIN B. HULL, MABEL E. JAooBsoN.

